John Dalton was born in 1766 and died in 1844. Around 1803 he developed the first atomic theory of matter. He was a meteorologist and was very important to study of chemistry. Dalton discovered the three basic laws of chemistry. The law of conservation of mass, The law of definite proportions, and The law of multiple proportions.

The law of conservation of mass was first stated by Antoine Lavoisier in 1789. It was a milestone in the development in the development of modern chemistry. It says to us today that there is no change in the total mass during a chemical reaction. If atoms are conserved during a chemical reaction the so is the mass.

The law of definite proportion is when two pure substances form a compound, they form in a definite proportion by mass. If the atoms in the elements have a fixed ratio then the mass proportions are also fixed. For example, when hydrogen and oxygen react to produce water the definite proportion is one gram of hydrogen for every eight grams of oxygen.

The law of multiple proportions was formulated by Dalton himself and was crucial to the establishment of atomic theory. It applies to when two elements form more than one compound. When one element combines with another to form more than one compound the ratio of the mass of the elements are simple whole-number ratios of each other. For example, in CO and in CO2, the oxygen-to-carbon ratios are 16:12 and 32:12.